You wouldn't answer deep personal questions from a random stranger on the street. Some questions might've been too invasive to answer were even some family and friends to ask them. Yet, it seems they felt like they should answer some interviewer they just met.
It's ultimately the responsibility of the person answering to select what and how much of themselves to share, depending on the relationship.
If the interviewer were to ask, "tell me your most embarrassing moment you had while having sex with someone", you wouldn't answer that. If they asked "tell me about the hardest day of your life" and the real, real answer was somehow that time you had that embarrassing moment while having sex with someone, you still wouldn't answer that. You would answer with what you'd be comfortable sharing with the random interviewer, if anything, else you can just decline the question.
The "embarrassing sex" is an exaggerated example. You can set your limits differently, in order to not feel
> completely emotionally drained
as the OP put it. Setting your limits such that your personal life is outside of what your comfortable sharing with the random interviewer would be appropriate.
GP comment on separating personal and work life said to imagine they tacked "... at work" at the end. You can also imagine "... that you're comfortable with sharing" as a more general rule.
In the US any employer who asks you about personal relationships during an interview is opening themselves up to an illegal discrimination lawsuit.
Asking personal questions could be seen as a way to elicit information about a protected status and thus give a rejected candidate ammunition for a claim, whether warranted or not.
It’s best to just keep questions focused on the workplace.
Even in the case of complete innocence, it often becomes a he-said-she-said situation, and the outcome boils down to which side presents the best set of “facts”.
I use quotes there because my broader experience with the court system routinely shows that it does not need be burdened by the “truth” or “facts”. That is probably because the regular cast in those venues are literally trained and practiced liars.
But if you're at a large enough company, you're absolutely getting sued for this from time to time, so you'll have the "how to not get sued" training before you're allowed to interview.
(Edit: this isn't limited to interviews. There's many, many examples of things that large companies will not touch due to legal risk, that smaller companies will... either due to lack of knowledge on the legal risk (maybe no legal department even exists yet?) or intentionally as a gamble)
It is illegal, and in my book also immoral to deny such a candidate, but the other side of the coin is there.
[1] https://en.wikipedia.org/wiki/Griggs_v._Duke_Power_Co.
[2] https://www.wsj.com/us-news/education/black-latino-teachers-...
[3] https://teachercertification.com/nystce/multi-subject-arts-a...
The specific cases you mention and the finer point is how do you demonstrate the necessity of a measure? Is high general IQ absolutely necessary for SWEs? Or is it enough to have a high logical reasoning, but don’t need spatial? Do you really need high IQ or is it enough to have a lot of practical experience with hands on skills? Do you need higher IQ to do zero to one development vs code maintenance? The devil’s always in the details with these kinds of questions, and it’s definitely not a blanket “you can’t use anything”.
It's supposed to mean "at work," but that doesn't at all mean that you can assume the interviewer is going to understand that.
Remember that interviews are 2-way. You don’t have to engage in someone’s bad faith or incompetent interviewing.